Being almost limitless and harmless, carbon is a very excellent material in terms of resources problem and environmental problem. The carbon material is diverse in the coupling configuration among atoms and is known to have various crystal structures such as, for example, diamond, diamond-like carbon, graphite, fullerene, carbon nanotube, and the like. Of these materials, diamond-like carbon which is an amorphous carbon film is attracted as a functional material which is excellent in mechanical properties such as, for example, wear resistance, solid lubrication and the like and which further has conductivity, visual ray/infrared ray transmittance, low permittivity, anti-oxygen barrier and the like.
Diamond-like carbon (DLC) is amorphous in crystal structure and is usually obtained on a surface of a substrate with amorphous carbon deposited thereon by a chemical vapor deposition (CVD) method. As the chemical vapor deposition (CVD) method, a plasma CVD method of parallel flat surface type is general which utilizes glow discharge generated by applying high-frequency electric power between two facing electrodes, as disclosed in Japanese unexamined, published patent application No. 6-256957. Specifically, a high-frequency electric power is applied between a high-frequency power supply electrode with a substrate arranged and an earthing electrode facing in parallel with the high-frequency power supply electrode, whereby the glow discharge is generated therebetween. By utilizing the glow discharge, a material gas (methane, ethylene or the like) is resolved to deposit a DLC thin film on the substrate.
However, where it is tried to form the DLC thin films all together on plural substrates in the aforementioned method, the plural substrates have to be arranged to be juxtaposed toward the high-frequency power supply electrode, and this needs an electrode of a large area corresponding to the total area of the substrates. Further, forming a film on a large area is technologically difficult, wherein the film thickness and the film composition of the DLC thin film are liable to be uneven on a substrate-by-substrate basis.
Also, in a PVD apparatus of another form for forming a film on a surface of a cylindrical substrate, the substrate has to be revolved in order to form the film over the whole surface of the cylindrical substrate, so that the PVD apparatus would become a high cost for a rotary mechanism provided therefor. Further, the rotary mechanism for revolving the substrate may make a cause of a trouble in the apparatus. In addition, the revolution of the substrate may be performed with the axis of the revolution being off-centered, in which case it is unable to obtain a thin film which is even in film thickness, composition and the like.
The present invention is made in order to solve the foregoing problems, and an object of the present invention is to provide a technology capable of forming amorphous carbon films efficiently at a low cost.